Conveyer for the transfer of workpieces, in particular workpiece carriers

ABSTRACT

A dual track conveying system for transporting workpiece carriers, has a main conveyor and, an auxiliary conveyor arranged parallel to the main conveyor. At least one transverse conveyor is arranged between the main conveyor and the auxiliary conveyor. The transverse conveyor is pivotally attached to the main conveyor. The moveable end of the transverse conveyor pivots up-and-to transfer the workpiece carriers from the transverse conveyor to the auxiliary conveyor. The transverse conveyor has a short belt and a long belt. The short belt is shorter than the long belt by the width of the auxiliary conveyor. A passive conveying track section following the path of the short belt is located in between the belts of the auxiliary conveyor to support one end of the work piece carrier when the moveable end of the transverse conveyor is in the raised position.

BACKGROUND OF THE INVENTION

The invention relates to a conveying system for transporting workpieces,in particular workpiece carriers.

Such a conveying device for transporting workpieces is disclosed inlaid-open publication DE 36 15 064 A1. This conveying device has twoparallel transport tracks and a transverse conveyor disposed betweenthem, wherein the transport tracks respectively have an outward locatedconveyor belt with an endless band belt guided on rollers, and arespectively inward located roller system disposed at a distance fromthe conveyor belt. The transverse conveyor has a support frame arrangedbetween the parallel transport tracks, which has an immobile centerpiece. Respectively one pivotably located end piece constitutes atransfer station. Each one of these end pieces intersects an inwardlocated roller system of a transport track and covers the free spacebetween the roller system and an outward located band belt of thetransport track. Respectively one lifting device is associated with thetwo end pieces, by means of which the end pieces can be pivoted intoseveral different vertical positions in respect to the transport track.

When designing such transverse conveyors it is necessary that the pivotaxis, around which the end pieces can be pivotably arranged, has adefined distance from the inward located roller system, so that apassage over the roller system disposed between the end pieces of thetransverse conveyor is made possible. Furthermore a part-intensiveembodiment in the pivot range is required, so that the band belt of theend pieces can be driven. Because of the division of the transverseconveyor into end sections and a center piece, a multitude of differentbelt lengths is required.

Furthermore, a conveyor device for transporting workpieces has alreadybecome known, which has two parallel transport tracks and a transverseconveyor arranged between them. This conveying device is embodied as asingle band belt system. The transverse conveyor, which constitutes aninserting or removal track, has a rigid frame which can be moved up ordown by means of a lifting cylinder arranged in the respective endsections.

In connection with such single band belt systems it is necessary thatthe workpiece be arranged on the workpiece carrier in such a way that aneven force distribution acts on the belt conveyor track as well as onthe inward located roller system. As soon as the load distribution ofthe workpiece on the workpiece carrier lies more on the roller system,an interference-free operation during inserting or delivering theworkpiece carrier can no longer be assured, since the frictional forceacting between the workpiece carrier and the single band belt could bereduced. For this reason the transport belt is subjected to greater wearbecause of friction.

BACKGROUND OF THE INVENTION

The conveying device in accordance with the invention has the advantagethat the conveyor track, which is embodied as one piece, allows asimplification of assembly and reduction in the assembly times.Furthermore, a modular construction is provided by this design. Theconveyor track embodied as one piece is provided in the form of a dualbelt conveyor, which permits a reduction of the mechanical. At the sametime dependable inserting and removal or a dependable transfer of theworkpiece carrier can be provided. Because of the design of the conveyortrack as a dual belt conveyor at a transfer station, where the workpiececarrier is intended to be conveyed out transversely in respect to theconveying direction, it is made possible that a dependable removal isprovided, even when the load distribution of the workpiece on theworkpiece carrier is uneven. An inward located conveying track at anopposite end of the previously described end section is embodiedshortened by the length of the transfer station. In the free spacebetween a conveyor track embodied as a dual belt conveyor and arrangedtransversely to it, a passive roller system is provided, which can alsobe moved up and down with an outward located belt conveyor track.Because the workpiece carrier is already in movement on the dual beltconveyor ahead of the transfer station, the dependable insertion into afurther conveyor track disposed transversely in respect to the conveyortrack can take place even prior with the single belt system, it is notnecessary for the workpiece carrier to be conveyed out of a position ofrest.

The end sections of the inserting and removal tracks are seated in anup- and down-movable manner in the transfer stations for transferringthe workpiece carriers from an inserting and/or removal track to a mainconveyor track and/or auxiliary conveyor track. A design which reducedstructural components and is cost-efficient can be provided by means ofthe rigid embodiment of the entire conveyor track over the length of theinserting and removal track. Furthermore, a considerable simplificationof assembly can be provided by the arrangement of a passive rollersystem in an end section of the conveyor tracks.

it is possible by means of the independent up- and down-movable endsections of the inserting and removal tracks to perform an insertingand/or removal process in one end section without the opposite endsection being affected by an inserting and/or removal process. At thesame time the end section and/or sections of the inserting and removaltrack can also take up a position in which the workpiece carrier passesover the transfer station, wherein this position also has no effect onan opposite end section.

The up and down movement of the end sections of the inserting and/orremoval track respectively takes place by means of a lifting elementdisposed in the end section, wherein a damping element is advantageouslydisposed between a support frame of the inserting and/or removal trackand the lifting element. By means of this, a damped and low-noisetransfer of the workpiece carrier from one conveying direction into aconveying direction extending transversely in respect to it. The tiltingmoments, which act on a conveyor track arranged transversely to theconveying direction, and which occur during the entry into the transferstation and when the workpiece carrier rests against a detent whichblocks it in the conveying direction, can be intercepted and absorbed.Furthermore, such a damped seating of the support frame has theadvantage that a compensation can take place during the tilting movementof the support frame, since the lifting elements can be arrangedindependently of each other in a lower, center or upper verticalposition in the respective end sections.

In an advantageous manner, in connection with the inserting and removaltracks it is provided that the end section, which is disposed oppositethe passive conveyor track, has ends of the conveyor tracks which areembodied to be of the same length. Because of this, belt conveyor trackscan project completely into the transfer station, so that the dependableremoval of the workpiece carrier is provided. It is simultaneouslypossible to achieve a modular construction by this embodiment.

The main and auxiliary conveyor tracks advantageously have an endsection located opposite the passive conveyor track, wherein the inwardlocated conveying track is shortened by at least the removal conveyortrack, which transversely enters the transfer station. It is possible bymeans of this to further increase the modular design of a transportconveying system. At the same time, dependable removal can again takeplace in a conveying direction, which is provided transversely inrespect to the previous conveying direction of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is represented in the drawingsin which:

FIG. 1, a partial section of a conveying device represented in aschematic top view,

FIG. 2, a schematic sectional representation of a lifting device with atransverse conveyor track which can be moved up and down,

FIG. 3, a working position of the transverse conveyor track,

FIG. 4, an alternative working position of the transverse conveyortrack,

FIG. 5, a further possible working position of the transverse conveyortrack.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A partial section of a main circulating track 10 of a conveying devicewith a forward transport track 11 and a return transport track 12, whichare arranged parallel with each other, is represented in FIG. 1. Areversing module 13 is respectively arranged at both ends of the forwardand return transport tracks 11, 12. The main circulating track 10 isrepresented by several main conveyor tracks 20 to 23, arranged onebehind the other, wherein the main conveyor tracks 20, 21 and, ifdesired, selectively still further main conveyor tracks, constitute theforward transport track 11, and the main conveyor tracks 22, 23, and, ifdesired, selectively still further main conveyor tracks, constitute thereturn transport track 12.

In the instant exemplary embodiment, the conveying device is embodied asa dual belt conveyor with the two conveyor tracks 11, 12, wherein eachconveyor track 20 to 23, for example, has its own drive for thetransport belts of the dual belt conveyor.

First and second auxiliary sections 26, 27 are arranged along the returntransport track 12. The auxiliary track sections 26, 27 are respectivelyconstituted by a removal module 28 with a removal track 29 and aninserting module 31 with an inserting track 32. The removal module 28and the inserting module 31 are arranged at right angles between the twomain conveyor tracks 22, 23, for example. A processing station 33 isprovided in the auxiliary section 26, where parts arranged on theworkpiece carrier 35 are processed.

The main conveyor track 22 and an auxiliary conveyor track 26 arrangedparallel to it, as well as the removal track 29 and the inserting track32, form a module 34, which will be explained by way of example. Severalsuch modules 34 can be disposed one behind the other, because of whichthe main conveyor tracks 20 to 23, arranged one behind the other,constitute a forward transport track 11 and a return transport track 12of a conveying device. The number of modules 34 can be selected as afunction of the number of processing stations 33.

The removal track 29 has an outward located conveyor belt 36 and aninward located conveyor belt 37, both of which are embodied as beltconveyor. A transfer station 28 is formed in the intersecting area ofthe main conveyor track 12 with an end section 52 of the removal track29, in which the two ends of the inward and the outward locatedconveying tracks 36, 37 are made of the same length. Opposite this atransfer station 39 is formed between an end section 53 of the removaltrack 29 and an end section 52' of the auxiliary conveyor track 26. Inthis case the conveying tracks 36, 37 of the removal track 29 mesh in atooth-like manner with an outward located conveying tack 41 and aninward located conveying track 42 of the auxiliary conveyor track 26.The driven or actively inward located conveying track 37 is made shorterthan the outward located active conveying track 36 of the removal track29 and terminates at the front toward the inward located conveying track42 of the auxiliary conveyor track 26. The inward located conveyingtrack 37 is supplemented by a passive conveying track section 43 in thetransfer station 39 between the outward located conveying track 41 andthe inward located conveying track 42, so that the inward locatedconveying track 37 and the passive conveying track section 43 have aconveying track 37 and the passive conveying track section 43 have aconveying track of the same length as the outward located conveyingtrack 36.

The passing conveying track section 43 is embodied as a roller track.This passive conveying track section 43 is disposed at a distance fromthe active inward located conveying track 37, which essentiallycorresponds to the width of the inward located conveying track 42 of theauxiliary conveyor track 26. The inward located conveying track 42 ofthe auxiliary conveyor track 26 extends in this free space formed by thespacing and terminates at the front toward the outward located conveyingtrack 36 of the removal track 29. At the front, the outward locatedconveying track 36 of the removal track 29 borders the outward locatedconveying track 41 of the auxiliary conveyor track 26. The transferpoint 39 is formed by means of this arrangement and embodiment of theend section 53 of the removal track 29 and the end section 52' of theauxiliary conveyor track 26. In the process the end section 53, 52' meshin the manner of teeth with each other. The transfer stations 39 and 51are designed in the same way.

A removal track 39 designed in this way then has the advantage that whena workpiece carrier 35 is transported out of the transfer station 38 inthe direction toward the transfer station 39, two driven or activeconveyor tracks 36, 37 are provided, so that the assured removal of theworkpiece carrier 35 out of the transfer station 38 is provided.

When the workpiece carrier 35 enters the transfer station 39, it istransported via the outward located conveyor track 36, wherein thepassive conveying track section 34 supplements the end section parallelwith it. Because of the workpiece carrier 35 already being moved in thetransport direction, one active conveying track 36 in the transferstation 39 can suffice to assure that the workpiece carrier 35 can becompletely moved into the transfer station 39.

In the transfer station 39, the end section 52' of the auxiliaryconveyor track 26 has outward and inward located conveying tracks 41, 4made of different length. A further transfer section 44 is provided,located opposite the transfer station 39, in which the workpiece center35 is placed from the auxiliary conveyor track 26 to the inserting track32. The auxiliary conveyor track 26 has an end section 53' of theoutward and inward located conveying tracks 41, 42 which corresponds tothe end section 53 of the removal track 29 and constitutes a part of thetransfer station 39. The outward located conveying track 41 extends overthe entire auxiliary conveyor track 26. The inward located conveyingtrack 42 is made shorter and borders an inward located and transverselyto the inward located conveying track 42 extending conveying track 47 ofthe inserting track 32. In an extension of the inward located conveyingtrack 42, a passive conveying track section 43 is provided between theinward located conveying track 47 and an outward located conveying track48 of the inserting track 32.

Such an embodiment of the intersection area with an inside locatedconveying track 57 and an outward located conveying track 58 is alsoprovided in a transfer station 51 of the inserting track 31 to the mainconveyor track 22.

Dependable removal from and insertion into the transfer stations 38, 39,44, 51 is provided by the end sections of the removal and insertingtracks 29, 32 and of the end sections of the main conveyor track 22 andauxiliary conveyor track 26.

The removal and the inserting modules 28, 31 are disposed in thetransfer stations 38, 39, 44, 51 to the upwardly and downwardly movablefor delivering and inserting the workpiece carrier 35. The up and downmovement of the end section 52 in the transfer station 38, 44, and ofthe end section 53 in the transfer station 39, 51 of the removal track29 and the inserting track 31 is respectively performed by means of alifting unit 54, which is associated with the end sections 52, 53 and isrepresented in a sectional view in FIG. 2. The lifting unit 54corresponds to a block cylinder, known per se. In this case it is adouble-acting lifting cylinder, which can move the end section 52, 53into different vertical positions. Alternatively it is also possible toprovide hydraulically, electromagnetically or electrically drivenlifting units.

A center position of the lifting unit 54 is represented in FIG. 2 inwhich it is possible, for example, to stop a workpiece carrier 35entering the transfer station 38 by means of a detent 64. To lift theworkpiece carrier 35 out of the main conveyor track 22, the lifting unit54 is charged with compressed air, so that the end section 52 is movedover a lifting path 56 into an upper vertical position. After theworkpiece carrier 35 has been conveyed out of the transfer station 38,the lifting unit 54 can be moved into a center position as representedin FIG. 2. In this case the lifting unit 54 can be unpressurized,wherein a restoring spring 57 and a pressure spring 58 can be placedinto equilibrium and transfer a base plate 59, on which the end section52 of the removal track 29 is seated, into a center position.

If a workpiece carrier 35 is to pass through the transfer station 38, asecond chamber of the lifting unit 54 is charged, so that a movement ofthe base plate over a stroke 61 into a lower position takes place.Because of this the end area 52 of the removal track 29 with the detent64 sinks downward, so that this transfer statio 38 can be passed. Afterthis has taken place, the lifting unit 54 can be made pressureless, bymeans of which it can again be moved into a center position.

The outward and inward located conveying track 36, 37 is respectivelydisposed via a damping element 62 in respect to the base plate 59 or anintermediate plate or adapter place 63, disposed on the base plate 59.These damping elements 62 are embodied to be elastic, so that a dampedseating of the removal track 29 and the inserting track 32 is provided.These damping elements can be made of an elastic plastic, or in the formof air cushions or other damping elements, which have a damping effectin the conveying direction as well as transversely to the conveyingdirection.

As soon as a removal of the workpiece carrier 35 out of the cushions orother damping elements, which have a damping effect in the conveyingdirection as well as transversely to the conveying direction.

As soon as a removal of the workpiece carrier 35 out of the mainconveyor track 22 into the removal track 29 is to take place, the endsection 52 in the transfer station 38 is placed into a center position,so that a detent 64 arranged on the inward located conveying track 37blocks in the conveying direction. The workpiece carrier 35 comes torest against the detent 64. In the course of this sudden stoppingmovement the end section 52 of the removal track 29 is subjected to atransverse force, which can be absorbed by the damping element andcompensated.

It is furthermore assured by means of such an elastic compensation, thatthe end areas 52, 53 of the removal track 29 can be positioned indifferent positions independently in respect to each other, since thedamping elements 62 are also embodied to be elastic and yielding in theconveying direction.

The passive conveying track section 43 in the end section 53 of theremoval track 29 is brought into different vertical positionsanalogously in place of the driven conveying track section 37 in the endsection 52.

Different vertical positions of the end areas 52 and 53 of the removaltrack 29 are represented in FIGS. 3, 4 and 5. This also applies to theinserting track 32. These FIGS. 3 to 5 only represent a selection ofpossible arrangements, wherein a lower, center and upper verticalposition of the removal track 29 in the transfer station 38 is shown byway of example for letting the workpiece carrier 35 pass, to stop it orto lift it out of the main conveyor track 22 in order to be subsequentlyconveyed off transversely to the main conveying direction. The verticalpositions of the end section 53 in the transfer station 39 have beenarbitrarily selected.

A lateral view of the removal track 29 is represented in FIG. 3. Theremoval track 29 has a drive 66, which drives the outward and inwardlocated conveying track 36, 37. The removal track 29 is seated via thedamping element 62 in respect to the lifting unit 54 in the end section52. The end section 52 is arranged in a lower vertical position 67. Inthis vertical position the end section 52 is lowered downwardsufficiently far so that a detent 64, which projects out the conveyingplane of the inward and outward located conveying track 36, 37, ispositioned underneath the conveying plane of the main transport track22. In this lower vertical position 67 the workpiece carrier 35 can passthrough the transfer station 38 and can be moved on in the conveyingdirection.

As represented by way of example, the end section 53 can be arranged inan upper vertical position 71. In this position a removed workpiececarrier 35 can move into the transfer station 39.

In FIG. 4 the end section 52 has been moved into a center verticalposition 68. Such a signal is issued by a control in those cases whereit is intended to transfer the workpiece carrier 35 via the removaltrack 29 to the processing station 33 in the auxiliary conveyor section26. In the center vertical position 68 the detent 64 projects past theconveying plane of the main conveyor track 22, by means of which theworkpiece carrier 35 is stopped in the transfer station 38.

In respect to the upper vertical position 71 in accordance with FIG. 3,the end section 53 has been moved into a center vertical position 72, bymeans of which the workpiece carrier 35 is placed on the auxiliaryconveyor track 26.

In FIG. 5 it has been detected by means of a signal transmitter, notshown, that a workpiece carrier 35 has entered the transfer station 38and has been positioned, because of which the control issues a signal osthat the end section 52 of the removal track 29 is moved into an uppervertical position 69 for lifting the workpiece carrier 35 out of thetransfer station 38 and to convey it off in the conveying direction ofthe removal track 29.

After the workpiece carrier 35 has been conveyed out of the transferstation 38 and the transfer station 39 has received a signal via asignal transmitter, that no workpiece carrier 35 is positioned therein,the end section 53 is moved into an upper vertical position 71, so thatthe workpiece carrier 35 lifted out of the main track 22 can enter thetransfer station 39. As soon as a signal transmitter of the transferstation 39 has detected that the workpiece carrier 35 is completelypositioned in the transfer station 39, the end section 53 is moved intoa lower vertical position, so that the former can be placed on theauxiliary conveyor track 26 and subsequently transported away.

This inserting and removal process as described for the removal track 29in FIGS. 3 to 5, analogously applies to the inserting track 31. In thiscase the main conveyor track 22 and the auxiliary conveyor track 26remain in a position of rest.

Monitoring of the transfer stations 38, 39, 44, 51 is made possible bysignal transmitters. In the same way it is possible to provideseparating elements in front of each transfer station 38, 39, 44, 51which are connected with the signal transmitters monitoring the transferstations 38, 39, 44, 51, so that a trouble-free operation can beassured.

We claim:
 1. A conveying system for transporting workpiece carriers,comprising a main conveyor track; an auxiliary conveyor track arrangedparallel to said main conveyor track; at least one transverse conveyortrack arranged between said main conveyor track and said auxiliaryconveyor track and arranged transversely in respect to said mainconveyor track and forming a transfer station having a width determinedby the lateral dimension of said auxiliary track; pivotablyup-and-downward moveable end section provided in said transverseconveyor track and transferring the workpiece carriers from saidtransverse conveyor track to said auxiliary conveyor track, said main,auxiliary and transverse conveyor tracks each being formed as dual beltconveyors with an inwardly located conveying track and an outwardlylocated conveying track, said inward located conveying track of saidtransverse conveyor track being shorter than the outward track width ofsaid transfer station; a passive conveying track section which followssaid inward located conveying track and disposed in said transferstation to terminate at a distance from the end of said auxiliaryconveyor track, said transverse conveyor track being rigid over itsentire conveying length, said transfer conveyor track having endsections arranged in said transfer station for up and down motion.
 2. Aconveying system as defined in claim 1, wherein said end sections ofsaid transverse conveyor track are movable up and down independently ofeach other.
 3. A conveying system as defined in claim 1, wherein saidtransverse conveyor track has at least one lifting unit disposed in saidend sections.
 4. A conveying system as defined in claim 1; and furthercomprising damping means arranged so that said end sections of saidtransverse conveyor track are seated in respect to said lifting unit bysaid damping means.
 5. A conveying system as defined in claim 4, whereinsaid damping means is deflectable as a function of a tilting movement ofsaid transverse conveyor track resulting from a lifting movement.
 6. Aconveying system as defined in claim 4, wherein said damping means isarranged in respect to said transverse conveyor track so as tocompensate forces directed transversely to conveying directions.
 7. Aconveying system as defined in claim 4, wherein said damping means islocated between said inward located conveying track and said outwardlocated conveying track.
 8. A conveying system as defined in claim 1,wherein said transverse conveyor track has an end section containing apassive conveying track section and an oppositely located end section,said inwardly located conveying track and said outwardly conveying trackhaving ends of a same length.
 9. A conveying system as defined in claim8, wherein said main conveyor track and said auxiliary conveyor trackhave said end section containing said passive conveying track sectionand an oppositely located end section, said inward located conveyortrack being shortened by at least an amount of said outward locatedconveying track of said transverse conveyor which enters said transferstation transversely.